chores: refactor module funds

[andrey-jef]

changelog:

• refactor code for better readability
• add type hints for the output of each function
• add error/exception handling for invalid input in fund_details and its dependent functions
• standardize column label of output dataframe to snake_case
• remove ambiguous input param lang, mode, decor from all of the functions' logic
• format code with ruff package
• update test_funds.py according to changes in funds.py

unit tests test_funds.py are all passed, before making PR.

vnstock on  chores/funds/refactor-funds-module [!?] is 󰏗 v0.2.8.7.dev.23  via  v3.9.18 via  dev-vnstock took 49s
❯ pytest .\tests\test_funds.py
====================================================================== test session starts =======================================================================
platform win32 -- Python 3.9.18, pytest-7.4.3, pluggy-1.3.0
rootdir: ~\my_workspace\andrey-jef\vnstock
plugins: cov-4.1.0
collected 10 items

tests\test_funds.py ..........                                                                                                                              [100%] 

====================================================================== 10 passed in 47.35s =======================================================================